Lexical processing is at the core of written and spoken language. The traditional view of the lexicon is akin to a "dictionary" with entries containing the phonological, orthographic, morphological and semantic information associated with each word. An alternative perspective is that lexical knowledge emerges from the dynamic interactions among distributed patterns of neural activity representing orthography, phonology, and semantics (with morphology reflecting learned systematic relationships among these representations). Computational (connectionist) models consistent with this perspective have accounted for a wide range of empirical phenomena in reading and language. Although highly successful, the models have not satisfactorily addressed cross-linguistic variation, how the orthographic, phonological, and semantic representations themselves develop, and certain specific empirical findings. Moreover, separate models address subsets of the relevant phenomena without clear evidence that their underlying assumptions are mutually consistent. To address these challenges, we propose to develop a single, longitudinal stimulation of lexical processing (Specific Aim 1), spanning early phonological development and lexical/morphological acquisition, reading acquisition in normal and dyslexic children, normal skilled reading and lexical/morphological processing, and patterns of acquired dyslexia in brain-damaged patients. Because developing a model of this breadth necessarily involves some compromise of depth, we also propose to develop focused stimulations, tightly coordinated with the longitudinal model, to address specific empirical phenomena in full detail (Specific Aim 2). Discoveries of critical design principles at this detailed level will be used to improve approximations within the longitudinal model. Focused simulations will address early phonological development and error patterns in child speech, morphological acquisition and generalization, normal skilled reading and acquired surface and phonological dyslexia, and cross-linguistic differences in morphological priming. Finally, we will carry out specific behavioral studies designed to test key assumptions of the framework (Specific Aim 3). Such studies will address the acquisition and generalization of derivational morphology, length effects in word and non-word reading, and the temporal dynamics of morphological processing.